This blurb can be found on the homepages of a couple of different aikido information websites. Usually listed under "Cool Facts".

"In a recent Florida court case, a man resisting arrest charged the officer involved for using excessive force when his wrist was broken during the application of an Aikido technique. The case reached the Florida State Supreme Court which ruled that the offender broke his own wrist by resisting the technique."

Although I'm having trouble finding any more precise documentation of this, it doesn't really seem to be "urban legend" territory.

Assuming that the events occurred as described, it seems to me that had the officer had an advanced level of aikido training, he would potentially have been capable of not only subduing the perpetrator but also of changing the technique so as not to allow the perpetrator to "break his own wrist". To me, this speaks of the possible dangers of having a working, yet limited knowledge of the art. In the case of LEO's, it seems safer for both parties, physically for the perp, and legally for the officer, to either train diligently and refine the techniques to as high possible level, or not to use them at all.

I must not fear.
Fear is the mind-killer.
Fear is the little-death that brings total obliteration...